On January 1, 2006, the first episode of series ten of Agatha Christie's Poirot, "The Mystery of the Blue Train," was made available for public viewing. This extended episode is based on the Agatha Christie book of the same name, which served as the source material. Guy Andrews wrote it, and Hettie Macdonald was the one who directed it.

Poirot becomes involved in the investigation of the brutal murder of American heiress Ruth Kettering and the disappearance of her fabulous ruby known as the 'Heart of Fire' while he is on the Blue Train traveling between Calais and Nice. Who is to blame for this? To put together the pieces of the tragic puzzle, Poirot interviews the girl's father, her maid, her estranged husband, her eccentric cousins, and a host of other peculiar passengers.